The booking process at the Sonoma County Jail is rote: Details of the arrest are noted, a round of questions asked and a photograph and fingerprint are entered into a computer system. Much of this information is public.

But transparency is sacrificed for a subset of inmates who press their right thumbs on what looks like a bar code scanner. The only information Sonoma County jail officials will reveal about them as a group is how many of them they release to Immigration and Customs Enforcement, or ICE.

These are the people tagged by Secure Communities, an immigration enforcement program that uses biometric technology to flag possible illegal immigrants booked into jail as a way of ultimately deporting serious criminals. It has resulted in hundreds of illegal immigrants being handed over to ICE.

The federal agency reports broad criminal categories, ranging from serious felonies to minor misdemeanors to “non-criminals.” But what is not clear are details about the arrest, the violations that landed them in jail in the first place.

Between March 2, 2010, and Feb. 28, 2011, of the 921 inmates released to immigration officials, 433 inmates who were neither convicted of the crime that put them in jail, nor had they ever been convicted of a crime, according to an ICE report released in March. Another 225 immigrants released to ICE had only recent or prior convictions for minor misdemeanor crimes.

The large number of illegal immigrants classified as noncriminals and low-level criminals has raised concerns among immigration attorneys and local advocates who question why so many immigrants are ending up in jail for minor offenses, such as driving without a license.

And without transparency and tracking of arrest records under the Secure Communities program, it's difficult to assess how illegal immigrants are ending up at the jail.

Michelle Crawford, a Santa Rosa immigration attorney, said family members of illegal immigrants often call her office in desperation, after an immigration “hold” has been placed. Undocumented immigrants facing serious criminal charges don't bother calling, she said.

“The people that call me on the phone and the people that come into my office, the majority are driving without a license or some other thing where no charge is filed,” she said.

“I'm not talking about DUIs, there are a large number of people who feel that's a dangerous crime,” Crawford said. “I'm talking about all these people who are simply stopped and asked, ‘Do you have a license? And if they don't, they have removal proceedings.”

The Press Democrat has submitted formal public records requests to the Sheriff's Office and ICE seeking specific arrest information about all the inmates released to ICE under Secure Communities. But the Sheriff's Office has denied these requests. Immigration and Customs Enforcement officials are preparing to respond to a similar request.

In rejecting the public records request, the Sheriff's Office cites a law that began as an emergency provision approved by the U.S. Congress after the Sept. 11, 2001, attacks that officials said was meant to protect investigations into terrorist threats.

County jail officials have also declined requests for nonpersonal, general arrest information related to illegal immigrants tagged by Secure Communities. Such information could help answer why hundreds of “non-criminal” illegal immigrants are ending up in jail.

“It's just a database,” said Sonoma County Assistant Sheriff Linda Suvoy, who runs the jail. “From where I sit, it hasn't changed anything. It's automatically sent to the FBI's biometric system,” Suvoy said.

Santa Rosa Police Chief Tom Schwedhelm said far more people are arrested than convicted because officers use different standards to arrest a person than prosecutors use to convict a person.

“It's ‘probable cause' to make the arrest versus ‘beyond a reasonable doubt' to convict a person with a 12-person jury,” he said, adding, “If you believe my officers are stopping people without reason, please let me know and give me the information and I'll check into it.”

The word for that is profiling, and a look at the arrest records would shed light on who is being picked up and why. Are the majority of those held for immigration holds there because of traffic stops? Local law enforcement officials have refused to say.

Sheriff Steve Freitas rejected the suggestion that local law enforcement uses a different standard for arresting people they suspect are illegal immigrants.

“Before Secure Communities (immigrant) advocates were accusing us of racial profiling and bias, but now everyone's fingerprints go through secure communities,” Freitas said.

Prior to Secure Communities, local jail staff pulled information about newly booked inmates who appeared to be in the country illegally, he said, adding that ICE agents then reviewed the reports a few times each week. Secure Communities takes out that step for jail staff, he said.

“It removes the idea of profiling and discrimination from the whole topic,” Freitas said.

It does at the jail. But what about at the point of interaction — and arrest — with officers and deputies?

Among the nine counties in the Bay Area, Sonoma County had one of the highest percentage of non-criminals released to ICE, 47 percent, second only Napa (55.56 percent) and Marin (49.78 percent) counties. However, both those counties released far fewer people to the federal agency.

Sonoma County District Attorney's officials said their record keepers don't track data regarding illegal immigrant involvement in the cases that cross their desks. Prosecutors are often unaware of a defendant's immigration status, said Christine Cook, office spokeswoman.

“We don't keep records like that,” Cook said.

Last year, The Press Democrat began requesting information about inmates released to ICE custody from the jail. The Sheriff's Office declined an October public records request for the names and other details gathered during booking of individuals taken from the jail by ICE agents. A records clerk said the request was an undue burden to the cash-strapped office, which is a legal response.

The Press Democrat responded in January with a pared-down request that was identical to a prior information request that sheriff's officials provided a year before. Nine days later, that request was also rejected. A clerk cited several government codes that offer exemptions to information that would otherwise be public.

The clerk also said the information requested included the inmates' criminal histories, however The Press Democrat request did not ask about prior convictions.

“The Sheriff's Office believes that the names of jail inmates are protected from disclosure under the California Public Records Act,” the clerk said in a Feb. 15 email.

Attorneys from separate firms that specialize in open government laws pointed to state laws that say local law enforcement “shall make public” arrest information.

“It's simply not clear to me how (the law) could authorize an agency to withhold the names of people who have been arrested,” said Katherine Keating, senior council for a San Francisco law firm Holme Roberts and Owen LLP, which staff's the First Amendment Coalition's legal hotline.

The Sheriff's Office clerk, in an email, later cited a federal law that prevents local agencies from releasing information about people in the Sonoma County Jail who have been flagged by federal immigration officials as possible illegal aliens.

The law grew out of an emergency provision Congress passed in 2002 to prevent the American Civil Liberties Union from getting information about people arrested in the New York City area and detained in the weeks and months following the Sept. 11, 2001, terrorist attacks.

Federal agencies do have authority to release details about federal inmates on a case-by-case basis, an ICE spokeswoman said this week. Immigration officials are required to respond to The Press Democrat's Freedom of Information Act request by Wednesday.

Last year, the National Day Laborer Organizing Network, represented by Center for Constitutional Rights and the Benjamin N. Cardozo School of Law Immigration Justice Clinic filed a lawsuit against ICE after a Freedom of Information request seeking documents related to Secure Communities was denied.

Bridget Kessler, one of the Law School clinic attorneys representing the immigrant-rights group, said a federal court judge compelled the immigration service to release documents. The federal agency now publishes quarterly reports about the immigrants it identifies under Secure Communities.

B. Loewe, a spokesman for the National Day Laborer Organizing Network, whose main office is in Los Angeles, said Secure Communities is actually a threat to immigrant communities because it keeps some victims from reporting crimes.

“Victims of crime including domestic violence survivors and witnesses of crimes now are second-guessing and deciding not to contact police, because of what might happen to them,” he said.

Supervisor Efren Carrillo said that while he trusts Freitas' assessment of the program, he wishes the county could “opt out” of it.

“I wish we had the power to opt out of Secure Communities,” he said. “In my opinion it creates a problem in our community. This program should have been focused on ensuring that repeat felons are not in our community.”

But he said “this is the sheriff's call it's not the Board of Supervisors' call.”

Law enforcement officials say they are obligated to uphold the law and stop people they believe are breaking it; they're just doing their job.